Aluminum-base alloy



Patented Apr. 23, 192 92 samurai. DANIELS, F DAYTON, OHIO.

ALUMINUM-BASE ALLOY.

. No IIrawing. I

This invention relates to the provision of an aluminum base alloy having a low copper content, and also containing small quantities of magnesium and silicon, which is 5 'possessed of very desirable physical properties in its cast condition, is of very light weight in proportion to its strength, and is capable of a very simple heat treatment by Which its physical properties are substantially improved. This heat treatment consists of heating for a period of time at a high temperature, subsequently (quenching in water or other suitable medium, and then artificially aging at a comparatively lowtemperature for a few hours.

More specifically an object of my inven tion is to provide for use in the cast condition an aluminum base alloy containing about 2.5% copper, 1.25% iron, .5% magnesium, and about .3% silicon, the balance of about 95.5% being aluminum;

Further objects will be more fullyset forth in detail in the following description and in the claims.

The approximate composition of the al-. 10y in accordance with this invention is as .follows: Copper, 2.5%, iron 1.25%, magnesium .5%, silicon .3%, and the balance aluminum. Such an alloy is. particularly useful in aircraft or aircraft engine and automotive construction, since it has a specific gravity of about 2 .7% and an ultimate v strength of about 24,000 lbs. per sq. in. as 'sand cast, and elongation of about 5% as P cast, which is an extremely good combination of strength and ductility, and not ordinarily obtainable in other alloys without heat treatment.

The copper content may be varied between 2.25% and 3.25%. Alloys with lower copper content than 2.25% do not respond materially to heat treatment. If the copper content exceeds the maximum stated, the

ductility "drops off rapidly.

The iron content may be between the limits of .5% and 1.5%. Its efl'ectis to increase the ductility apparently without modifying the tensile strength. The magnesium and silicon are present in the ratio may be varied from 25% to .75%, the silicon being varied between .2% and 175%.

The effect of increasing the magnesium is to embrittle the alloy. Decreasing it below 5 .4% prevents a complete response to heat of about 1.7 to 1. The'magnesium content Application filed March 27, 1925. serial'lqo. 18,883.

treatment. The aluminum content varies from 94.7 to 96.5%.- It will be observed that as the copper content decreases, the total content of magnesium and silicon together is increased in 'a fairly constant manner, al-

rding to any arithmetical.

though not acc ratio, according to the following table':

Copper content. Silicon. Magnesium.

s The amount of iron present may be varied according to the characteristics of the metal desired. The alloy, being free from zinc has desirable casting properties and strength at elevated temperatures.

The best results are obtained by having the copper presentdn quantities between 2.3 and 2.7 the iron between 1 and 1.4%, the and .65%, and the magnesium between 141% silicon between 25% and .5%, the balance of course being aluminum.

' This aluminum alloy may be very materially affected by heat'treatment. The preferred heat treatment consists in heating the alloy to about 950 F. for about two hours, then quenching in water and artificially aging for about two hours at a temperature of about 212 orup to 300 It has been found that the ultimate strength will be increased by this heat treatment to about 30,000 lbs. per sq. in., the elongation being then from 3 to, 5%. Aging at higher temperatures than as above noted may some times be used, but-such higher temperatures increase strength and hardness at the expense of ductility. 3

I am aware that my invention issusc'eptible of modifications within limits and intend that the invention ',be defined by the following claims: I

1. An aluminum base alloy containing copper between 2.25% ,and 3%; iron, .75% to 1.5% and containing a few tenths of a percent each of magnesium and silicon, the ratio of the magnesium to the silicon beingabout 1.7 to 1. I

2. An aluminum base alloy copper between.2.25% to 3%; iron, between .7 5% and 1.5% and containing a few tenths of a per cent each of magnesium and silicon,

containing 3, An aluminum base alloy containing aluminum between 94.7 and- 96.5%, copper between 2.25%and 3%, iron (75. to 1.5%, magnesium .25 to .7 5%, silicon .2 to .7 5%, the 5. sum of the magnesium, silicon and copper being between 3.25% and 4.25% of the whole.

cording to the following proportions: Alu-' minum 95.47%, copper 2.5%, iron 1.25%,

y ,4. An aluminum base alloy containing magnesium .5%, and silicon 3%.

copper 2.3 to 2.7%, iron to 1.4%, magnesium .4 to 155%, silicon .25 to .5% and 0 the balance aluminum, the sum of the mag-- In testimony whereof, I aflix my signature.

SAMUEL DANIELS. 

